Hi Henri...Based on best understanding of your doubt, when a block is created, ALL the transactions within the block gets represented collectively by its Merkle root. Each transaction will have an associated Merkle proof (the path) which shows its consistency with that specific Merkle root. Here, the root path is not altered by HK. If a transaction needs to be verified independently, it is done by reconstructing the Merkle path based on the intermediate nodes’ hash values. For instance if transaction TD needs to be verified, Merkle root will be reconstructed using HD, HC, HAB, HEFGH and HIJKLMNOP.